Iceland turns CO2 into stone

Iceland turns CO2 into stone

The Hellisheidi power plant is the world’s largest geothermal facility. It provides the energy for Iceland’s capital, Reykjavik, plus power for industry, by pumping up volcanically heated water to run turbines

Iceland has done it again. No, its not football. It’s even better. They successfully turned CO2 into stone!

In Iceland, scientists and engineers are fighting climate change by injecting CO2 deep into volcanic rocks.

This new process involves mixing CO2 and hydrogen sulfide released by the plant with water. And than, injecting the mixture into underground layers of basalt.Within a few months, the mixture is converted into rock hard carbonate.

By pumping the stuff into volcanic basalt, the CarbFix Project has converted 95 percent of the CO2 emissions from a geothermal plant into solid carbonate minerals.



Iceland’s Hellisheidi geothermal power plant is the world’s largest. It is cleaner than those run on fossil fuels, but still emits carbon dioxide by venting volcanic gases.

The finding may help address a fear that so far has plagued the idea of capturing and storing CO2 underground: that emissions could seep back into the air or even explode out.

Iceland power plant

The Hellisheidi power plant is the world’s largest geothermal facility. It provides the energy for Iceland’s capital, Reykjavik, plus power for industry, by pumping up volcanically heated water to run turbines. But the process is not completely clean; it also brings up volcanic gases, including carbon dioxide and nasty-smelling hydrogen sulfide.

Solidified within less than two years

The pilot project called Carbfix, started in 2012. The plant began mixing the gases with the water pumped from below and re-injecting the solution into the volcanic basalt below.

In nature, when basalt is exposed to carbon dioxide and water, a series of natural chemical reactions takes place, and the carbon precipitates out into a whitish, chalky mineral. But no one knew how fast this might happen if the process were harnessed for carbon storage.

Previous studies have estimated that in most rocks, it would take hundreds or even thousands of years. In the basalt below Hellisheidi, 95% of the injected carbon was solidified within less than two years.

Martin Stute, a hydrologist at Columbia University’s Lamont-Doherty Earth Observatory and professor of environmental science at Barnard College:

“This means that we can pump down large amounts of CO2 and store it in a very safe way over a very short period of time. In the future, we could think of using this for power plants in places where there’s a lot of basalt – and there are many such places.

Most of the world’s seafloors are made of the porous, blackish rock, as are about 10 percent of continental rocks.

The local basalt contains plenty of calcium, iron and magnesium, which are needed to precipitate out carbon. Experiments showed that large amounts of water would also have to be added to make the reaction go—another departure from previous projects, which have just pumped down pure carbon dioxide.

Global interest

Geothermal companies around the world have shown interest in the technology. The main stumbling block beyond the needed basalt, seems the water required: about 25 tons for every ton of CO2.

  • Separation and injection of CO2 in most other projects has been estimated to cost a steep $130 or so a ton.
  • The Hellisheidi operation has an advantage in that it largely uses the plant’s existing infrastructure to re-inject the solution, and doesn’t bother purifying the CO2. Its cost is only $30 a ton.

More CO2 initiatives

Recently, other companies have looked at other innovative ways to use up power plants’ carbon emissions.

We need to deal with rising carbon emissions. This is the ultimate permanent storage. Turn it back to stone.


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